Inertial Accumulator (IA) for onboard power supply of spinning and non-spinning projectiles and Directed Energy Projectiles

ABSTRACT

The Inertial Accumulators, which transform G-forces and/or rotational energy of a projectile into rotational energy of flywheel, store it and convert into electrical one to feed onboard electronics and/or high-energy emitter of Directed Energy Projectiles.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention relates to U.S. Provisional Application No. 61/148172.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable.

INCORPORATED-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK

Not Applicable.

FIELD OF THE INVENTION

The present invention relates to onboard power supplies of rockets and projectiles. More particularly, the present invention relates to projectile power supplies utilizing G-forces and providing high-power electrical output for short period of time, or, even, very-high-power electric pulse feeding onboard generator of Directed Energy Projectiles.

BACKGROUND OF THE INVENTION

Because the onboard power source must provide relatively high electrical power for a short time of projectile flight, conventional chemical batteries is not optimal solution. Moreover, so-called “Directed Energy Projectiles”—special-purpose projectiles containing a high power RF or laser emitter—requires enormous electrical power discharged as a very short multi-megawatt pulse on final part of projectile's trajectory. It is obvious that conventional sources of electrical power can not provide such power.

The most commonly used chemical batteries are silver-zinc, lithium or nickel-cadmium rechargeable ones. Silver-zinc batteries, for example, can release its energy for minutes, but can not be stored for years. Lithium batteries, such as Li/CFx or LiSOCl2—the most advanced electrical-chemical power sources can be discharged for minutes and stored for years, but some of them, when operate, are heated at high temperature and, sometimes, produce exhaust gases that have to be removed. Also, at low ambient temperature its power capability significantly declines. There are “ampoule mechanical activation batteries” where electrodes and electrolyte are separated to increase the storing time, but its activation time is about a few seconds that is too long for guided projectiles. And, non-of them can produce high peak electrical power for a fraction of second.

Therefore, the onboard power supply has to utilize an alternative principle of electricity generation and storage rather than electrical-chemical battery and one of them is the Inertial Accumulator. When the projectile is fired, it is affected by enormous G-forces for the fraction of second. Also, a projectile fired from riffled barrel start spinning with high spinning rate exceeding 20,000 rpm. These forces could be utilized to provide onboard energy feeding the equipment and, even, high-energy-pulse generators of Directed Energy Projectile. Here, G-forces or projectile rotation accelerate relatively massive flywheel—rotor of an electrical generator up to 20,000 rpm and the generator start producing electrical power that could be enough to feed onboard electrical equipment for the time of projectile flight and/or provide very high peak energy feeding equipment of Directed Energy Projectile.

Here is the list of possible devices based on different physical principles that could be used in the onboard power supplies:

-   -   Flywheel-based Inertial Accumulator (IA)—the object of the         present invention. It utilizes G-forces and/or the projectile         rotation and can works with both, spinning and non-spinning         projectiles, has simple and reliable design, low weight and         size. It can provide electrical power for all flight time of the         projectile or/and produce very high electrical power for a short         time.     -   Compressed air power supply charged by G-forces utilizes         pressurized air that is compressed by free-moving massive piston         in the time of projectile acceleration. The compressed air feeds         turbine that rotates electrical generator. Theoretically, such         power supply can provide enough power to feed onboard equipment,         but its design is more complicated and includes separate turbine         and generator, reservoir for compressed air, etc. So, mass and         size of such device is bigger than IA's. Estimating calculations         reveal that its characteristics are significantly worse than         IA's ones.     -   Electrical generator for spinning projectiles utilizing the         projectile rotation in Earth magnetic field has very simple         design that includes rotor coil and electrical circuit only.         Estimating calculations reveal that such power supply can         provide a few watts of electrical power at 12 VAC at 20,000 rpm,         but the output very depends on Earth magnetic field (that         depends on the geographic location), trajectory and the flight         direction. So, in some cases it could declines in many times,         for example, when the projectile flights in North or South         directions. Moreover, it works for spinning projectiles only and         the outer shell of the projectile has to be made of         magnet-transparent material such as fiberglass, for example.         Therefore, because its output is not stable, it is not a         reliable power source and it can not be recommended for onboard         power supply. Also, it can not provide enough energy for         Directed Energy Projectiles.     -   Battery of piezoelectric elements charged by stress produced by         G-forces contains piezoelectric elements placed between two         massive structural elements of the projectile. When the         projectile is fired the elements compress the piezoelectric         producing electrical charge that theoretically could be         utilized. Estimating calculations reveal that efficiency of such         power supply is very low. The coefficient of transformation         (efficiency) of a piezoelectric is about 20% only and calculated         electrical charge that is induced on the surface of the element         will be about 0.004 C (at 50 kg of effecting mass and 50,000 G).         Moreover, a piezoelectric battery has high internal electrical         resistance so producing high voltage. Because of this, the         piezoelectric battery can not be recommended as the main source         of electrical power, but it could be used as additional one in         combination with IA-based power supplies to ignite, for example,         gas discharge in lasers.     -   Air turbine electrical generator driven by external air stream         includes air turbine mechanically connected to electrical         generator. It could be installed in different parts of the         projectile, for example, close to projectile base and utilize         the difference of air pressure on outer shell and missile base         (base vacuum). Estimating calculations reveal that such power         supply can provide a few watts of electrical power to feed         onboard devices, but it require air intake and exhaust openings         in missile body, which have to be closed in the time of storing         and opened when the missile is fired. Moreover, it is the device         interacting with outside air, raising the aerodynamic drag and         worsening projectile stability, unlike the devices described         above that are completely internal ones. So, in some cases such         power supply can be used with some limitations as a low power         onboard electrical source for rotating and not-rotating         projectiles.

Therefore, the review and analysis of alternative principles of electrical power generation for small-size onboard power supplies reveal that the best (among the listed ones) is the principle of inertial accumulation of energy. Moreover, IA is the only device that can produce high power electrical pulse for a short period of time that is vital for some application, such as Directed Energy Projectile.

OBJECT OF THE INVENTION

It is an object of the present invention to provide an Inertial Accumulators to feed onboard electronics and/or Directed Energy Projectiles.

SUMMARY OF THE INVENTION

The present invention alleviates mentioned disadvantages of conventional power sources of projectiles by means of utilization of Inertial Accumulator (IA), which converts rotational energy of a projectile and/or G-forces into rotational energy of flywheel, stores and transforms it into electrical power feeding onboard electronics and/or Directed Energy Projectiles. IA of the present invention can be utilized in both, spinning and non-spinning projectiles providing electrical supply feeding onboard electronics for all flight time, or release it for a short time producing megawatts of electrical power that is essential for Directed Energy Projectiles carrying, for example, very-high-power microwave pulse generator. IA—the object of the present invention—is a completely autonomic device and does not require any maintenance. It starts operating when the projectile is fired and continues working all flight time. For fast rotating projectile, its design is maximally simplified so diminishing the size and mass of the device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION—IA-DRIVEN POWER SUPPLY FOR SPINNING PROJECTILES

The scheme of the invention—IA-based power supply for spinning projectiles—is depicted in FIG. 1.

The flywheel 1 is carried in bearings 2 and additionally supported by axial bearings 3; it starts working when the projectile accelerates. The flywheel rim 4 consists of number of magnets 4 mounted on the disk 5. The stator coils 6 mounted on the projectile's shell 7 surrounds the flywheel rim. The rectifier circuit and electrical stabilizer are mounted in the electrical unit (not shown on FIG. 1).

When the projectile is fired it start spinning, but the flywheel still not spinning yet because of flywheel inertia. Therefore, the flywheel rotates about projectile body and its energy can be used for electricity generation. Thus, it starts generating electrical power immediately after the projectile is fired and continues producing it in the time of flight. So, it does not require any mechanics charging the flywheel.

The energetic capacity of such accumulator depends on the inertia momentum of the flywheel and relative spinning rate of the flywheel about the projectile body. The energy could be released for the whole time of projectile flight feeding the onboard equipment, or for a fraction of second providing high-peak electrical power for a pulse energy emitter (for Directed Energy Projectile), such as laser, electromagnetic pulse generator, etc. Also, it can do both—feed the equipment and, in designated moment produce high power electrical pulse. IA could be mechanically connected to a separate electrical generator, or flywheel itself can be a rotor of an electrical generator as depicted in FIG. 1.

Total energy capacity of that Inertial Accumulator is determined by momentum of inertia of the flywheel and its angular speed according to the formula:

E=Jω ²/2,

Where: E -energy,

-   -   J—axial momentum of inertia (J=Σr² m),     -   ω—angular speed of rotation (radian/sec).         To provide the maximal momentum of inertia the mass of flywheel         has to be concentrated on the flywheel's rim. In this case, a         relatively massive rim 4 is mounted on thin disk 5 that has to         be strong enough to hold the rim in the condition of high         centripetal and inertial forces stretching and twisting the         disk.

Such IA built in 155-mm shell and having the flywheel of 0.3-kg mass at 20.000 rpm of initial spinning rate accumulates about 10 kJ of kinetic rotational energy and can provide about 300 watts of power for 30 seconds of projectile flight or 100 kW for 0.1 sec. This power supply is cylindrically shaped with the axial thickness of 40 mm and total mass of 0.6 kg.

Simplified variant of this embodiment is schematically shown on FIG. 2. Here, the shaft 12 of flywheel 1 is connected to the shaft 13 of separate electrical generator 11 via coupling 14, wherein the generator is firmly fastened on projectile's shell. In this case, functions of flywheel and generator are separated that allows using any kind of electrical generators having suitable characteristics, but mass and volume of such power supply is higher in comparison with the previous variant.

ANOTHER EMBODIMENTS OF THE INVENTION—IA-DRIVEN POWER SUPPLY FEEDING PULSE GENERATOR OF DIRECTED ENERGY PROJECTILES

The scheme of this embodiment is depicted in FIG. 3.

Here, a part of projectile is used as a flywheel. The projectile consists of outer rotating shell 1 and not-rotating core 2 having equal inertia momentums. The array of permanent magnets 3 is mounted on the outer shell 1. Rotor coils 4 are mounted on the surface of the core 2. The outer shell and core are jointed by bearings 5 and 6, and symmetry axes of the core and outer shell are aligned. The core 2 contains payload 7 (electrical circuit and high-energy emitter of Directed Energy Projectile, such as laser, electromagnetic pulse generator, etc.). The appropriate configuration and design of stator magnets 3 and rotor coils 4 can provide necessary current and voltage. Even though the coils of the generator could be destroyed for a fraction of second because of very high peak power, the properly designed electrical circuit can release full energy for very short period of time feeding pulse energy emitters.

Theoretically, the maximal energy of the flywheel could reach a quarter of total rotational kinetic energy of the projectile when momentums of inertia of the outer shell and core are equal. In this case, when those two parts start exchanging rotational energy—start producing power—the spinning rate of the outer shell decreases and the core accelerates until the spinning rates of both parts becomes equal. Finally, Inertia Accumulator becomes completely discharged and spinning rate of the projectile becomes equal to ½ of the initial one.

Total rotational energy of 155 mm shell at 20,000 rpm will be about 210 kJ. So, maximal available for IA rotational energy is about 53 kJ. This energy released for 30 seconds of projectile flight provides about 1.7 kW of power output. Also, if the energy is released for 0.05 sec, it can provide up to 1-megawatt power output that could be utilized in Directed Energy Projectiles.

ANOTHER EMBODIMENTS OF THE INVENTION—IA-DRIVEN POWER SUPPLY FOR NON-SPINNING PROJECTILES

In the case of non-spinning projectiles, G-forces could be utilized to charge Inertial Accumulator. The design of such IA, which is more complicated than for rotating ones because it has to contain mechanics transforming the energy produced by G-forces into rotational one, is depicted in FIG. 4.

The flywheel 1—the rotor of electrical generator—contains set of permanent magnets 2 mounted on the flywheel rim. In the center, it has specially threaded sleeve 3. The flywheel sits on a top of the hollow shaft 4 mounted on the base 5, engages the thread and can move along the shaft. The thin pin 6 prevents the flywheel from accidental moving. The bearing 7 enclose the shaft 4 on another end. The coil 9 of the stator of the electrical generator is mounted on the base 5. The rectifier circuit and electrical stabilizer are mounted in the electrical unit 10 placed inside the shaft 4.

When the projectile is fired, the flywheel is exposed to G-forces. So, the flywheel shears the pin 6 and starts moving along the shaft and rotating. When the flywheel reaches the end of the shaft, it disengages the thread and becomes tightly fitted on the bearing 7 and supported by the thrust bearing 8. Therefore, the electrical generator starts working.

Total kinetic energy of 155 mm projectile at 1,000 m/sec is about 25 MJ that is 100 times more than its rotational energy, but its utilization requires an axially moving body inside the projectiles. It has to pass some distance inside the projectile under acceleration to obtain kinetic energy that could be transformed into rotational one or electricity. The energy can be estimated according to the formula:

E=m a h,

Where: m—mass of the body,

a—acceleration,

h—the distance passed by the body under the acceleration (along direction of acceleration vector).

Therefore, to obtain the same kinetic energy of 10 kJ as the IA of rotating projectiles of the preferred embodiment, the internal body with mass of 0.5 kg has to pass about 10 cm along the projectile's axis. So, this device will take more volume inside the projectile and be slightly more massive than the similar one utilizing projectile's rotation. Also, such device utilizing G-forces of non-spinning projectiles could be used as an onboard power supply, but can not provide enough energy for Directed Energy Projectiles, unlike IA-driven power supply of spinning ones. Thus, such IA with flywheel of 0.5-kg mass at 20.000 G of initial acceleration will have about 10 kJ of kinetic energy that could be transformed into flywheel rotation and provide about 300 watts of power for 30 seconds of projectile flights. This power supply could be estimated as cylindrically-shaped one with the axial thickness of 100 mm and total mass of 1.0 kg as depicted in FIG. 4.

THE DRAWINGS

FIG. 1 depicts the preferable embodiment of the present invention—IA for spinning projectiles.

FIG. 2 schematically depicts another variant of preferable embodiment of the present invention utilizing separate generator.

FIG. 3 depicts another embodiment of the present invention—IA for spinning projectiles feeding a pulse generator of Directed Energy Projectiles.

FIG. 4 depicts another embodiment of the present invention—IA for non-spinning projectiles. 

1. An Inertia Accumulator (IA) for spinning projectiles that comprises: a. a free-rotating flywheel having a shaft and bearings in which said shaft can freely rotates, wherein flywheel axis is aligned with rotation axis of said projectile; b. a separate electrical generator firmly fastened on inner surface of shell of said projectile, which has a shaft mechanically connected to said shaft of said flywheel, wherein, when said projectile is fired, it start spinning, whereas said flywheel stills not spinning yet because of flywheel mechanical inertia; thus, said flywheel starts spinning about shell of said projectile, said flywheel starts rotating said shaft of said electrical generator so transforming rotational energy of said flywheel into electrical one.
 2. The Inertia Accumulator (IA) for spinning projectiles of claim 1, wherein the free-rotating flywheel of claim 1 contains a set of permanent magnets on its rim, and the spinning projectile of claim 1 additionally comprises a firmly fastened on inner surface of the projectile's shell stator coil encircling said flywheel; thus, the separate electrical generator of claim 1 is eliminated and said Inertia Accumulator works as an electrical generator.
 3. The Inertia Accumulator (IA) for spinning projectiles of claim 1 feeding a pulse generator of Directed Energy Projectiles, which comprises spinning shell and free-rotating core that have equal inertia moments, wherein an array of permanent magnets is mounted on inner surface of shell of said projectile, and a rotor coil is mounted on outer surface of said projectile core, which contains a payload; thus, it allows maximally utilizing rotational energy of the projectile.
 4. An Inertia Accumulator (IA) for a non-spinning projectile comprising: a flywheel, which is a rotor of an electrical generator, that contains a set of permanent magnets mounted on rim of said flywheel, wherein said flywheel has threaded sleeve, a hollow shaft, which axis is aligned with axis of said projectile, having a thread on outer cylindrical surface; said shaft is mounted on a base that is firmly attached to shell of said projectile, wherein said flywheel rests atop of said shaft and thread of said shaft is engaged to thread of said sleeve that allows said flywheel start rotating when it is sliding along said shaft under G-forces, a thin pin preventing said flywheel from accidental moving, a bearing enclosing said shaft on another end, a coil of stator of said electrical generator mounted on said base, a rectifier circuit and electrical stabilizer mounted as an electrical unit that is placed inside said hollow shaft; wherein, when said non-rotating projectile is fired, said flywheel is exposed to G-forces; so, said flywheel shears said pin and starts moving along said shaft and rotating; and when said flywheel reaches end of said shaft, it disengages from thread of said shaft and becomes tightly fitted on said bearing allowing said flywheel continue rotating; therefore, said flywheel together with said stator starts working as an electrical generator so generating electricity. 